Vehicle rollover protection roof geometry and structure

Abstract

A vehicle geometry for rollover crush resistance is created by determining a center of mass providing a roll axis and establishing a roof line contact surface spaced from the center of mass by a hoop radius substantially equal to a major radius of roll contact from the roll axis. As a first embodiment, the roof line contact surface is established in original designs for vehicles as a monocoque structure. As a second embodiment, provided as an original equipment manufacture (OEM) item or retrofit structural assembly, an arcuate member shaped as a byte of the hoop radius is employed and is mounted between two side rails with additional structural supports for the arcuate member on a nominally flat roofline.

1. A vehicle geometry for rollover crush resistance comprising:
 a center of mass providing a roll axis; 
 a roof line contact surface spaced from the center of mass by a continuous hoop radius substantially equal to a major radius of roll contact from the roll axis. 
 
   
   
     2. The vehicle geometry as defined in  claim 1  wherein the hoop radius is equal to the major radius +10% and −5%. 
   
   
     3. The vehicle geometry as defined in  claim 1  wherein the hoop radius is faired into the sides of the vehicle. 
   
   
     4. The vehicle geometry as defined in  claim 3  for a vehicle with A pillars wherein the hoop radius is faired into the profile of the A-pillars. 
   
   
     5. The vehicle geometry as defined in  claim 1  wherein the roof line contact surface is structurally supported as a monocoque structure. 
   
   
     6. The vehicle geometry as defined in  claim 2  wherein the hoop radius is optimized as equal to the major radius +5%. 
   
   
     7. A method for increasing vehicle rollover crush resistance comprising:
 establishing a center of mass for determination of a roll axis; and 
 shaping a roll contact surface of the vehicle to a hoop radius which minimizes far side aggressivity. 
 
   
   
     8. The method as defined in  claim 7  wherein the step of shaping the roll contact surface comprises establishing a hoop radius substantially equal to a major radius of roll contact from the roll axis. 
   
   
     9. The method as defined in  claim 8  wherein the step of establishing a hoop radius provides a radius equal to the major radius +10% and −5%. 
   
   
     10. The method as defined in  claim 9  wherein the radius is optimized as equal to the major radius +5% and −0%. 
   
   
     11. The method as defined in  claim 7  further comprising the step of fabricating the roof with a monocoque structure to create the hoop radius. 
   
   
     12. The method as defined in  claim 7  further comprising the step of fairing the hoop radius into the vehicle sides. 
   
   
     13. The method as defined in  claim 12  for a vehicle with A pillars wherein the step of fairing comprises fairing the hoop radius into the A-pillar profile. 
   
   
     14. A rollover protection system for a vehicle comprises an arcuate member extending from a nominally flat roofline, said arcuate member having a continuous hoop radius substantially equal to a major radius of roll contact from a center of mass providing a roll axis. 
   
   
     15. The rollover protection system defined in  claim 14  wherein the arcuate member is faired to the sides of the vehicle. 
   
   
     16. The rollover protection system defined in  claim 15  wherein the hoop radius is equal to the major radius +10% and −5%. 
   
   
     17. The rollover protection system defined in  claim 16  wherein the hoop radius is optimized as equal to the major radius +5% and −0%. 
   
   
     18. The rollover protection system as defined in  claim 14  further comprising side rails mounted substantially at the intersection between the nominally flat roofline and each side of the vehicle, said arcuate member attached to the side rails. 
   
   
     19. The rollover protection system as defined in  claim 18  further comprising angled forward supports extending from the arcuate member to the roofline. 
   
   
     20. The rollover protection system as defined in  claim 18  further comprising angled rearward supports extending from the arcuate member to the roofline. 
   
   
     21. The rollover protection system as defined in  claim 19  further comprising a front lateral member extending between the side rails and providing an attachment for the forward angled supports. 
   
   
     22. The rollover protection system as defined in  claim 20  further comprising a midships lateral member extending between the side rails and providing an attachment for the rearward angled supports. 
   
   
     23. A rollover protection system comprising:
 at least one arcuate member extending from a nominally flat roofline of a vehicle, said arcuate member faired to the sides of the vehicle and having a continuous hoop radius substantially equal to a major radius of roll contact from a center of mass providing a roll axis; 
 side rails mounted substantially at the intersection between the nominally flat roofline and each side of the vehicle, said arcuate member attached to the side rails; 
 a plurality of angled forward supports extending from the arcuate member to the roofline and attached to a front lateral member extending between the side rails; 
 a plurality of angled rearward supports extending from the arcuate member to the roofline and attached to a midships lateral member extending between the side rails. 
 
   
   
     24. The rollover protection system as defined in  claim 23  wherein the hoop radius is equal to the major radius +10% and −5%. 
   
   
     25. The rollover protection system defined in  claim 24  wherein the hoop radius is optimized as equal to the major radius +5% and −0%. 
   
   
     26. The rollover protection system defined in  claim 23  wherein the arcuate member, side rails, forward and rearward supports, front and midships lateral members are provided as a retrofit kit. 
   
   
     27. A rollover protection system comprising:
 at least one arcuate member extending from a nominally flat roofline of a vehicle, said arcuate member faired to the sides of the vehicle and having a hoop radius substantially equal to a major radius of roll contact from a center of mass providing a roll axis; 
 side rails mounted substantially at the intersection between the nominally flat roofline and each side of the vehicle, said arcuate member attached to the side rails; 
 a plurality of angled forward supports extending from the arcuate member to the roofline and attached to a front lateral member extending between the side rails; 
 a plurality of angled rearward supports extending from the arcuate member to the roofline and attached to a midships lateral member extending between the side rails; 
 a plurality of angled rearward supports extending from the arcuate member to the roofline and attached to a midships lateral member extending between the side rails, said arcuate member, side rails, forward and rearward supports, front and midships lateral members provided as a retrofit kit; and 
 an aerodynamic fairing.